Figure 23.25: An example of an aquatic marine biome, pack ice. ( 24 )The concept that the biosphere is itself a living organism, either actually or metaphorically,
is known as theGAIA hypothesis. The hypothesis explains how biotic and abiotic factors
interact in the biosphere. It considers Earth itself a kind of living organism. Its atmosphere,
heliosphere, and hydrosphere are cooperating systems that yield a biosphere full of life. Lynn
Margulis, a microbiologist, added to the hypothesis, specifically noting the ties between the
biosphere and other Earth systems. For example, when carbon dioxide levels increase in the
atmosphere, plants grow more quickly. As their growth continues, they remove more carbon
dioxide from the atmosphere. Many scientists are now devoting their careers to organizing
new fields of study, such as geobiology and geomicrobiology, to examine these relationships.
For a better understanding of how the biosphere works and various dysfunctions related to
human activity, scientists have simulated the biosphere in small-scale models. Biosphere
2 (Figure23.26) is a laboratory in Arizona which contains 3.15 acres of closed ecosystem
BIOS-3 was a closed ecosystem in Siberia; and Biosphere J is located in Japan.
Direct human interactions with ecosystems, including agriculture, human settlements, ur-
banization, forestry, and other uses of land, have fundamentally altered global patterns of
biodiversity and ecosystem processes. As a result, vegetation patterns predicted by conven-
tional biome systems are rarely observed across most of the planet’s land surface. On terms
of the human impact on biomes and ecosystems, the study of ecology is now more important
than ever. Scientists that study ecology will move us toward an understanding of how best
to live in and manage our biosphere.